Air Force grounds F-22 fleet yet again

The United States Air Force temporarily halted operations for its $77.4 billion fleet of F-22 Raptors this week after several of the plane’s pilots reported bizarre symptoms linked with oxygen deprivation.

Pilots at a military base in Alaska are reporting symptoms linked with hypoxia after being engaged in missions onboard the Air Force’s F-22 Raptor aircraft, a Lockheed Martin-made stealth jet that runs at around $143 million-per-plane. There have been at least three incidents reported out of the Elmendorf-Richardson Joint Base in the last two weeks which is now causing concern within the US Air Force.

Only last May, the Air Force temporarily suspended the Raptor program in order to investigate a series of mysterious claims at the time. The craft was cleared to go back in the sky this past September, but pilots have reported nine instances of hypoxia-like symptoms in the six months since.

In the two years before the initial ground, there were only 12 reported instances similar to what pilots say they experience now. Coupled with November 2010 crash that was tied to an oxygen disruption during a training mission, mounting problems regarding the Raptors continues to raise concern over the incredibly expensive endeavor.

The US Air Force has around 180 jets in the Raptor line, which costs taxpayers nearly $78 billion to maintain. In brief history of the craft, however, this recent grounding marks the fifth time a substantial selection of the fleet has been grounded.

All three of the latest incidents involve pilots reporting symptoms related with hypoxia, a condition that occurs when the brain is deprived of oxygen. As a result, pilots can experience problems such as dizziness, confusion and poor judgment, explains the National Institute of Health. The November 2010 crash that killed Captain Jeff Haney — the only casualty thus far for the fleet — was tied to a malfunction in the oxygen system.

Internal officials say that they have investigated each instance but given the latest rash of occurrences, have been unable to remediate the problem. Col. Regina Winchester tells ABC News now that the planes are being grounded for “review,” although, in the past, she says, "In each case, appropriate procedures were applied” to examine potential malfunctions.

Lt. Gen. Herbert Carlisle, a high-ranking Pentagon official, adds to the Air Force Times that despite ongoing investigation, the Defense Department has been unable to explain the ongoing reports of hypoxia-like symptoms.

“We have looked at everything on that system [to] the nth degree, and the bottom line is that there’s no smoking gun,” explains Carlisle.

The Air Force grounded the fleet out of the Alaska base on Tuesday this week, although the planes were slated to be back on the runway Wednesday for routine missions.

Last year the Air Force grounded the F-22 fleet, but also all 20 of the F-35 crafts over an issue with the plane’s electrical system. That incident in August 2011 marked the third time that the F-35 fleet had been taken out of commission following malfunctions, essentially removing the biggest, most expensive — and assumingly the best — that the Air Force has to offer.